/// <summary>
/// extension sắp xếp theo thứ tự giảm dần
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="propertyName"></param>
/// <returns></returns>
/// created by: ntkien 01.06.2020
public static IQueryable <T> ApplyOrderByDesc <T>(this IQueryable <T> source, string propertyName) where T : class
{
var expression = PropertyAccessorCache <T> .Get(propertyName);
if (expression == null)
{
return(source);
}
MethodCallExpression resultExpression = Expression.Call(
typeof(Queryable),
nameof(Queryable.OrderByDescending),
new Type[] { typeof(T), expression.ReturnType },
source.Expression,
Expression.Quote(expression));
return(source.Provider.CreateQuery <T>(resultExpression));
}
public static IQueryable <T> ApplyWhere <T>(this IQueryable <T> source, string propertyName, object propertyValue, ColumnTypeEnum propertyType, ExpressionOperationEnum operation) where T : class, new()
{
string proName = Utility.GetStandardPropertyName(new T(), propertyName);
// 1. Retrieve member access expression
var mba = PropertyAccessorCache <T> .Get(proName);
if (mba == null)
{
return(source);
}
//2.Try converting value to correct type
object value;
//cách kiểm tra xem có phải là kiểu nullable ko?
var uType = Nullable.GetUnderlyingType(mba.ReturnType);
string typeName = (uType != null) ? uType.Name : mba.ReturnType.Name;
try
{
value = Utility.ConvertValueByType(propertyValue, typeName);
}
catch (SystemException ex) when(
ex is InvalidCastException ||
ex is FormatException ||
ex is OverflowException ||
ex is ArgumentNullException)
{
return(source);
}
//convert
var typeCompare = uType != null? uType:mba.ReturnType;
var body = Expression.Convert(mba.Body, typeCompare);
var valExpress = Expression.Constant(value, typeCompare);
// 3. Construct expression tree
Expression eqe = null;
if (operation == ExpressionOperationEnum.Equals)
{
eqe = Expression.Equal(body, valExpress);
}
//lớn hơn
else if (operation == ExpressionOperationEnum.GreatThan)
{
if (typeName.Equals("DateTime", StringComparison.OrdinalIgnoreCase))
{
eqe = Expression.GreaterThan(body, Workaround_3361((DateTime)value));
}
else
{
eqe = Expression.GreaterThan(body, valExpress);
}
}
//lớn hơn hoặc bằng
else if (operation == ExpressionOperationEnum.GreatThanEqual)
{
if (typeName.Equals("DateTime", StringComparison.OrdinalIgnoreCase))
{
eqe = Expression.GreaterThanOrEqual(body, Workaround_3361((DateTime)value));
}
else
{
eqe = Expression.GreaterThanOrEqual(body, valExpress);
}
}
//nhỏ hơn
else if (operation == ExpressionOperationEnum.LessThan)
{
if (typeName.Equals("DateTime", StringComparison.OrdinalIgnoreCase))
{
eqe = Expression.LessThan(body, Workaround_3361((DateTime)value));
}
else
{
eqe = Expression.LessThan(body, valExpress);
}
}
//nhỏ hơn hoặc bằng
else if (operation == ExpressionOperationEnum.LessThanEqual)
{
if (typeName.Equals("DateTime", StringComparison.OrdinalIgnoreCase))
{
eqe = Expression.LessThanOrEqual(body, Workaround_3361((DateTime)value));
}
else
{
eqe = Expression.LessThanOrEqual(body, valExpress);
}
}
LambdaExpression expression = null;
//chứa
if (operation == ExpressionOperationEnum.Contains || operation == ExpressionOperationEnum.StartsWith || operation == ExpressionOperationEnum.EndsWith)
{
string methodName = "Contains";
if (operation == ExpressionOperationEnum.StartsWith)
{
methodName = "StartsWith";
}
else if (operation == ExpressionOperationEnum.EndsWith)
{
methodName = "EndsWith";
}
var method = typeof(string).GetMethod(methodName, new[] { typeof(string) });
var valExpression = Expression.Constant(value, mba.ReturnType);
var paramExp = Expression.Parameter(typeof(T), "x");
var memberExpression = Expression.Property(paramExp, propertyName);
var methodExp = Expression.Call(memberExpression, method, valExpression);
expression = Expression.Lambda <Func <T, bool> >(methodExp, paramExp);
}
else
{
expression = Expression.Lambda(eqe, mba.Parameters[0]);
}
// 4. Construct new query
MethodCallExpression resultExpression = Expression.Call(
null,
Utility.GetMethodInfo(Queryable.Where, source, (Expression <Func <T, bool> >)null),
new Expression[] { source.Expression, Expression.Quote(expression) });
return(source.Provider.CreateQuery <T>(resultExpression));
}
